EXPECT_FALSE(cache.ValidateAndUpdateFileSignature(filename, 321));
  TF_EXPECT_OK(ReadCache(&cache, filename, 0, 16, &out));
  EXPECT_EQ(calls, 2);
}

TEST(RamFileBlockCacheTest, PassThrough) {
  const string want_filename = "foo/bar";
  const size_t want_offset = 42;
  const size_t want_n = 1024;
  int calls = 0;
  auto fetcher = [&calls, want_filename, want_offset, want_n](